I was diagnosed in 1998 after my first big relapse in 1997, but long after my first attack which was in 1984.
How long relapses happen varies massively. Some people have enough to get diagnosed and then never have another one. Some people have them frequently, every year. The rest of us are somewhere in between. But how often we get them, how badly we get them, how long they last, the damage they do, etc, varies between people and also within the same person.
I tend to have bad years when I have lots of relapses so I make some changes in my life (go part-time; start Copaxone; stop work completely; start Rebif) and I then have some good years when hardly anything of note happens. I’m just coming out of a bad couple of years and am hoping for the normal good years now (at least!).
The best way to learn about MS is to have a look at this site & the MS Trust site and order whatever booklets that you think you would like to read. If you are into research, I recommend the MSRC news feeds as well as the multiple sclerosis research blogspot (you can set up a RSS feed straight to your email box for both of these). Some MS nurses run sessions on understanding MS too - you could call your nurse and ask. Another way is to join your local MSS branch - there will be people there with lots of experience of dealing with MS (although they aren’t always very up to date, in my experience anyway!).
If you’re in Hillingdon (London) then you can come to my group and I’ll fill you in as best I can
There’s a lot of info out there on the internet. Try not to get overwhelmed! And try to stick to the main websites in the beginning at least; there are a lot of fruitcakes out there!